safec  2.1
Safe C Library - ISO TR24731 Bounds Checking Interface
memcmp_s.c
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1 /*------------------------------------------------------------------
2  * memcmp_s.c - Compares memory
3  *
4  * October 2008, Bo Berry
5  *
6  * Copyright (c) 2008-2011 Cisco Systems
7  * All rights reserved.
8  *
9  * Permission is hereby granted, free of charge, to any person
10  * obtaining a copy of this software and associated documentation
11  * files (the "Software"), to deal in the Software without
12  * restriction, including without limitation the rights to use,
13  * copy, modify, merge, publish, distribute, sublicense, and/or
14  * sell copies of the Software, and to permit persons to whom the
15  * Software is furnished to do so, subject to the following
16  * conditions:
17  *
18  * The above copyright notice and this permission notice shall be
19  * included in all copies or substantial portions of the Software.
20  *
21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
22  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
23  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
24  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
25  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
26  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
28  * OTHER DEALINGS IN THE SOFTWARE.
29  *------------------------------------------------------------------
30  */
31 
32 #include "safeclib_private.h"
33 #include "safe_mem_constraint.h"
34 #include "safe_mem_lib.h"
35 
36 
72 errno_t
73 memcmp_s (const void *dest, rsize_t dmax,
74  const void *src, rsize_t smax, int *diff)
75 {
76  const uint8_t *dp;
77  const uint8_t *sp;
78 
79  dp = (uint8_t*) dest;
80  sp = (uint8_t*) src;
81 
82  /*
83  * must be able to return the diff
84  */
85  if (diff == NULL) {
86  invoke_safe_mem_constraint_handler("memcmp_s: diff is null",
87  NULL, ESNULLP);
88  return (RCNEGATE(ESNULLP));
89  }
90  *diff = -1; /* default diff */
91 
92  if (dp == NULL) {
93  invoke_safe_mem_constraint_handler("memcmp_s: dest is null",
94  NULL, ESNULLP);
95  return (RCNEGATE(ESNULLP));
96  }
97 
98  if (sp == NULL) {
99  invoke_safe_mem_constraint_handler("memcmp_s: src is null",
100  NULL, ESNULLP);
101  return (RCNEGATE(ESNULLP));
102  }
103 
104  if (dmax == 0) {
105  invoke_safe_mem_constraint_handler("memcmp_s: dmax is 0",
106  NULL, ESZEROL);
107  return (RCNEGATE(ESZEROL));
108  }
109 
110  if (dmax > RSIZE_MAX_MEM || smax > RSIZE_MAX_MEM) {
111  invoke_safe_mem_constraint_handler("memcmp_s: dmax/smax exceeds max",
112  NULL, ESLEMAX);
113  return (RCNEGATE(ESLEMAX));
114  }
115 
116  if (smax == 0) {
117  invoke_safe_mem_constraint_handler("memcmp_s: smax is 0",
118  NULL, ESZEROL);
119  return (RCNEGATE(ESZEROL));
120  }
121 
122  if (smax > dmax) {
123  invoke_safe_mem_constraint_handler("memcmp_s: smax exceeds dmax",
124  NULL, ESNOSPC);
125  return (RCNEGATE(ESNOSPC));
126  }
127 
128  /*
129  * no need to compare the same memory
130  */
131  if (dp == sp) {
132  *diff = 0;
133  return (RCNEGATE(EOK));
134  }
135 
136  /*
137  * now compare sp to dp
138  */
139  *diff = 0;
140  while (dmax > 0 && smax > 0) {
141  if (*dp != *sp) {
142  /*** *diff = *dp - *sp; ***/
143  *diff = *dp < *sp ? -1 : 1;
144  break;
145  }
146 
147  dmax--;
148  smax--;
149 
150  dp++;
151  sp++;
152  }
153 
154  return (RCNEGATE(EOK));
155 }
156 EXPORT_SYMBOL(memcmp_s)
errno_t memcmp_s(const void *dest, rsize_t dmax, const void *src, rsize_t smax, int *diff)
Compares memory until they differ, and their difference is returned in diff.
Definition: memcmp_s.c:73
void invoke_safe_mem_constraint_handler(const char *msg, void *ptr, errno_t error)
Invokes the currently set constraint handler or the default.